Physicists: Increasing CO2 By 100% Only Reduces Radiative Cooling To Space By An Imperceptible 1%

“An increase in low cloud cover of only about 1% could largely compensate for the doubling of CO2.” – Wijngaarden & Happer, 2025

Ph.D physicists detail just how insignificant CO2 is as a factor in climate change, revealing that doubling the CO2 concentration from 400 ppm to 800 ppm – a 100% increase – hypothetically reduces radiative heat loss to space by just 1%.

Since CO2 has only risen by 50% since 1750 (280 ppm to 420 ppm), CO2’s total greenhouse effect influence in reducing outgoing radiation has thus far been in the range of tenths of a percentage point. A less than 1% change in outgoing radiation over hundreds of years is not even detectable amid the noise of outgoing radiation measurement. Observation error in measuring Earth’s outgoing radiation is 33 W/m², for example.

Furthermore, this negligible CO2 greenhouse effect impact is only a calculated value for an atmosphere that is perpetually cloud-free. As clouds are present 60-70% of the time, this clear-sky-only condition only occurs in an imaginary world – an atmosphere that doesn’t exist.

In contrast to CO2’s role within the greenhouse effect, the greenhouse effect of clouds is tens of times more influential. As Drs. Wijngaarden and Happer point out in their conclusion, all that is needed to offset or wipe out the impact of doubling CO2 is a mere 1% change in cloud cover.

Since cloud cover changes of well more than 1% occur routinely, both from year-to-year and decadally, the role of CO2 within the greenhouse effect is rendered insignificant, if not irrelevant.